1. Field of the Invention
The present invention relates to a construction machine having a cooling construction for cooling an engine and hydraulic devices, and particularly to a compact hydraulic excavator.
2. Description of the Related Art
In the past, in a hydraulic excavator as a construction machine, a hydraulic pump for supplying pressure oil to a hydraulic driving system such as a work attachment is driven by an engine. A radiator is provided to cool the engine. Radiation devices, for example, such as a hydraulic pump and a working oil tank other then the engine are air cooled by placing cooling air taken in from outside by operation of a cooling fan in contact therewith.
More specifically, a so-called pusher fan type cooling construction having a cooling fan arranged upstream the radiator will be described. In this cooling construction, cooling air taken into a body cover by operation of the cooling fan is introduced into the radiator and is placed in contact with the hydraulic devices also. Cooling air risen in temperature by heat exchange between the radiator and the hydraulic devices is released externally of the body cover.
However, in a compact hydraulic excavator in which the engine is arranged directly below an operator""s seat, the size of an upper frame is extremely small. Therefore, there is no room for scattering and arranging the engine and the devices. When the engine and many devices are to be installed on the upper frame whose area is limited, the devices have to be necessarily integrated in a limited area. For example, a working oil tank and a fuel tank are arranged close to each other. In this case, since a temperature of working oil rises during operation, a temperature of the working oil tank rises. The fuel tank also rises in temperature accordingly. Particularly where a fuel tank made of resin is used, when the temperature exceeds a heat resistant temperature of resin, trouble such as deformation of the tank occurs.
As described above, in the conventional compact hydraulic excavator, when the devices are integrated, the devices arranged in the vicinity of the radiation devices are thermally affected by the rise of temperature of the radiation devices. With this, the devices arranged in the vicinity thereof become risen in temperature. In order not to be affected by heat, a certain space may be provided between the devices, or only the radiation devices may be isolated thermally. However, when the space is provided between the devices, the devices cannot be gathered and arranged. As a result, the compactness at which the compact hydraulic excavator is aimed cannot be achieved. Further, the parted arrangement of only the radiation devices results in less realization in the compact hydraulic excavator restricted by a space.
It is an object of the present invention to provide a construction machine having a cooling construction capable of cooling efficiently even in a state that devices such as a working oil tank and a fuel tank are gathered and arranged, thereby realizing compactness.
The construction machine according to the present invention comprises: an engine received within a body cover of the construction machine, a hydraulic pump connected to an output shaft of the engine, a cooling fan taking cooling air into the body cover, and a plurality of devices to be cooled gathered and arranged in the vicinity of the hydraulic pump, these devices being arranged so as to form a cooling air passage parallel with the direction of the output shaft between the devices.
Since in this case, the cooling air passage provided between the devices gathered and arranged is formed in parallel with the output shaft of the engine, the cooling air taken into the body cover is guided into the cooling air passage and go around the devices. Because of this, the devices can be cooled efficiently. Further, the plurality of devices to be cooled are gathered and arranged in the vicinity of the hydraulic pump connected to the output shaft of the engine so that the cooling air may pass through the devices efficiently. Because of this, a plurality of devices can be gathered and arranged within the body cover with a limited space. Thereby, the compactness of the body can be realized.
Preferably, a cooling air intake is provided in the body cover on substantially an extending line of the cooling air passage. The arrangement of the cooling air intake may be in the vicinity of the extending line of the cooling air passage.
Since in this case, the cooling air passage is provided on substantially an extending line of the cooling air intake, the cooling air is guided into the cooling air passage smoothly.
In the present invention, the plurality of devices to be cooled comprise the cooling construction including a working oil tank, a fuel tank, and a battery.
Since in this case, even if the working oil tank, the fuel tank, and the battery are gathered and arranged, the cooling air passage is secured, radiation of the working oil tank is cooled by ventilation of cooling air. Thereby, the fuel tank and the battery arranged in the vicinity of the working oil tank can be prevented from being risen in temperature.
Further, preferably, if a cooling construction is employed in which a fuel tank and a battery are arranged on one lateral side and the other lateral side, respectively, of the working oil tank.
Since in this case, the fuel tank and the battery are arranged on each side of the working oil tank, refueling and maintenance are facilitated.
Further, preferably, if a cooling construction is employed in which a shoulder part of the working oil tank has a stepwise recess, and a battery is arranged in the recess.
In this case, the working oil tank and the battery can be combined substantially face to face. With this, the gathering rate of devices can be enhanced. Moreover, it is not necessary to provide a battery fixing bracket on the upper rotating body. With this, the number of parts can be reduced.
Further, preferably, a cooling construction is employed in which a notch part is formed so as to avoid an interference with the hydraulic pump below the working oil tank.
In this case, the working oil tank can be arranged close to the hydraulic pump to a degree not to interfere with the hydraulic pump. With this, the gathering rate of devices can be enhanced.
The aforementioned cooling construction can be applied to both a pusher fan type in which a cooling fan is arranged upstream the radiator and a suction fan type in which a cooling fan is arranged downstream the radiator. In the suction type, cooling air after being heat exchanged by the radiator is introduced into the devices to be cooled. On the other hand, in the pusher fan type, cooling air taken from outside is first introduced into the devices to be cooled, because of which the pusher fan type has an advantage that the cooling efficiency is high.
Further, the hydraulic pump according to the present invention is connected in series to an output shaft of the engine. A plurality of devices are gathered and arranged making use of a space around the hydraulic pump. The hydraulic pump is positioned opposite to the cooling fan.